Semiconductor device having damascene interconnection structure that prevents void formation between interconnections having transparent dielectric substrate

ABSTRACT

A semiconductor device is made up of a first insulating layer having a through hole; a first interconnection which includes a first conductive layer, a first barrier layer, and a first main interconnection, and a second interconnection connected to one of the first conductive layer and the first barrier layer. Accordingly, the semiconductor device can avoid a problem where the material of the first main interconnection transfers from a portion connected to the second interconnection due to electromigration to form a void, with the result that the first interconnection is disconnected from the second interconnection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of application Ser. No. 10/397,369 filed on Mar. 27, 2003, which is a continuation application of application Ser. No. 10/127,599, filed on Apr. 23, 2002, now U.S. Pat. No. 6,759,747, which is a continuation application of application Ser. No. 09/329,249 filed on Jun. 10, 1999, now U.S. Pat. No. 6,400,031, which are hereby incorporated by reference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a semiconductor substrate, and more particularly, the present invention relates to a damascene interconnection structure.

This application is a counterpart of Japanese application Serial Number 163304/1998, filed Jun. 11, 1998, the subject matter of which is incorporated herein by reference.

2. Description of the Related Art

In general, it is difficult to form a pattern by etching a Copper (Cu) interconnection. In a formation of the Cu interconnection, an insulating layer such as a SiO₂ or BPSG is formed on a semiconductor substrate. Then, a recess is formed in the insulating layer so as to shape the Cu interconnection. Then, Cu is buried in the recess. As a result, the Cu interconnection buried in the recess is a so-called damascene interconnection, which is formed on the semiconductor substrate.

Such a damascene interconnection is formed as shown in FIG. 1A-FIG. 1D. FIG. 1A-FIG. 1D are cross sectional views showing a damascene interconnection structure of a conventional art.

A first interconnection pattern recess is formed using photolithography techniques and etching techniques in a first SiO₂ film 12 having a thickness of 1 μm on the semiconductor substrate 10. Then, a barrier layer 16 such as a TiN is formed on the first SiO₂ film 12 in the first interconnection pattern recess. Then, Cu is formed on the entire surface and the Cu is polished with alkaline solution having a colloidal-silica, so-called CMP (chemical mechanical polishing) method. As a result, a first interconnection including a main interconnection 19 is formed which is made up of the Cu, as shown in FIG. 1A. A second SiO₂ film 22 having a thickness of 1 μm is formed on the first SiO₂ film 12 where the first interconnection 18 was formed. Then, a through hole 55 is formed in the second SiO₂ film 22 so that a center portion of an upper surface of the first interconnection 18 is exposed, as shown in FIG. 1B.

A second interconnection pattern recess 24 is formed so that a predetermined portion of the through hole 55 remains. Then, a barrier layer 26 such as TiN is formed in the remaining through hole 55 and the second interconnection pattern recess 24, as shown in FIG. 1C.

Then, Cu is formed on the entire surface using a sputtering technique, and the Cu is polished using a CMP method. As a result, a second interconnection 28 including a main interconnection 29 which is made up of the Cu is formed, as shown in FIG. 1D.

In the conventional art of the method for forming the interconnections, it is desirable to avoid a problem wherein the Cu transfers from a portion connected to the second interconnection due to electromigration, whereby a void is formed at the connected portion, and the first interconnection is disconnected from the second interconnection.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductor device that can avoid the above noted problem wherein the Cu transfers from a portion connected to the second interconnection due to electromigration, whereby a void is formed at the connected portion, and the first interconnection is disconnected from the second interconnection.

According to one aspect of the present invention, for achieving the above object, there is provided a semiconductor device including a first insulating layer having a through hole; a first interconnection including a first conductive layer, a first barrier layer, and a first main interconnection; the first conductive layer formed on the first insulating layer in the first through hole; the first barrier layer formed on the first conductive layer; the first main interconnection formed on the first barrier layer so as to bury the through hole; and a second interconnection connected to one of the first conductive layer and the first barrier layer.

According to another aspect of the present invention, for achieving the above object, there is provided a semiconductor device including a first insulating layer having a through hole; a first interconnection including a first conductive layer, a first barrier layer, and a first main interconnection; the first conductive layer formed on the first insulating layer in the first through hole; the first barrier layer formed on the first conductive layer; the first main interconnection formed on the first barrier layer so as to bury the through hole; and a second interconnection connected to one of an edge portion of the first conductive layer exposed from an upper surface of the first insulating layer and an edge portion of the first barrier layer exposed from an upper surface of the first insulating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes claims particularly pointing out and distinctly claiming the subject matter that is regarded as the invention, the invention, along with the objects, features, and advantages thereof, will be better understood from the following description taken in connection with the accompanying drawings, in which:

FIG. 1A-FIG. 1D are cross-sectional views showing a damascene interconnection structure of a conventional art.

FIG. 2 is a plan view showing a damascene interconnection structure according to a first preferred embodiment.

FIG. 3 is a cross-sectional view showing a damascene interconnection structure according to the first preferred embodiment.

FIGS. 4A-4F are cross-sectional views showing a method for forming damascene interconnections structure according to the first preferred embodiment.

FIGS. 5A-5F are cross-sectional views showing a method for forming damascene interconnections structure according to a second preferred embodiment.

FIG. 6 is a plan view showing a damascene interconnection structure according to a third preferred embodiment.

FIG. 7 is a cross-sectional view showing a damascene interconnection structure according to a third preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A storage device and an alternate processing method for defective sectors of a storage device according to first and second preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 2 is a plan view showing a damascene interconnection structure according to a first preferred embodiment. FIG. 3 is a cross-sectional view showing a damascene interconnection structure according to the first preferred embodiment.

As shown in FIG. 2 and FIG. 3, a first damascene interconnection structure is preferably made up of a first insulating layer, as a first SiO₂ 12, having a first through hole, and a first interconnection 18 that is buried in the first through hole. The first interconnection 18 is preferably made up of a first conductive layer such as a first TiN film 16 a, a first barrier layer such as a first Ti film 17 a, and a first main interconnection 19. The first TiN film 16 a is formed on the first SiO₂ 12 in the first through hole. The first Ti film 17 a is formed on the first TiN film 16 a. The first main interconnection is formed on the Ti film 17 a so as to bury the first through hole. The first through hole has a first extending direction and a second extending direction which is longer than the first extending direction, and is formed so that the second extending direction corresponds to the flow of electrons in the first interconnection 18 which is formed in the first through hole.

A second damascene interconnection structure is preferably made up of a second insulating layer, as a second SiO₂ 22, having a second through hole, and a second interconnection 28 which is buried in the second through hole. The second interconnection 28 is preferably made up of a second conductive layer such as a second TiN film 26, a second barrier layer such as a second Ti film 27, and a second main interconnection 29. The second TiN film 26 is formed on the second SiO₂ 22 in the second through hole. The second Ti film 27 is formed on the second TiN film 26. The second main interconnection 29 is formed on the second Ti film 27 so as to bury the second through hole. The first interconnection 18 is connected to one of the second TiN film 26 and the second Ti film 27 of the second interconnection 28. The second interconnection 28 is connected to one of the first TiN film 16 a and the first Ti film 17 a. The second interconnection 28 has a protrusion portion where the second interconnection 28 is connected to the first interconnection 18. The protrusion portion of the second interconnection 28 is connected to the first interconnection 18 via the first through hole.

In the structure mentioned above, when a voltage so as to become a high voltage is applied to the first interconnection 18 and a voltage so as to become a low voltage is applied to the second interconnection 28, electrons flow from the second interconnection 28 to the first interconnection 18. The Cu atoms in the first main interconnection 19 of the first interconnection 18 move in the opposite direction of electron flow because of electromigration. As a result, voids are formed in the first main interconnection 19 of the first interconnection 18. However, since the second interconnection is connected to the first Ti 17 a, the first Ti 17 a can maintain electrical connection between the first and second interconnections.

FIGS. 4A-4F are cross-sectional views showing a method for forming a damascene interconnections structure according to the first preferred embodiment.

As shown in FIG. 4A, a first SiO₂ film 12 as a first insulating film with a thickness of 1 μm is formed on a semiconductor substrate 10. First interconnections recesses 14 with a depth of 500 nm are formed in regions which first interconnections are formed, using a photolithography technique and plasma etching with a mixed gas of C₂F₈ and O₂.

As shown in FIG. 4B, TiN films 16, 16 a with a thickness of 30 nm are selectively formed on the first SiO₂ film 12 in the first interconnection recesses 14. Ti films 17, 17 a with a thickness of 5 nm are formed on the TiN films 16, 16 a. A CVD (Chemical Vapor Deposition) method and CMP (Chemical Mechanical Polishing) method are used for forming the TiN films 16, 16 a and the Ti films 17, 17 a. Then, Cu is buried in the first interconnection recesses 14 and then is polished until the first SiO₂ film 12 is exposed, using the CMP method. As a result, a first main interconnection 19 is formed in the first interconnection recesses 14. Therefore, a first interconnection 18 which is made up of the TiN films 16, 16 a, the Ti films 17, 17 a, and the first main interconnection 19, are formed in the first interconnections recesses 14.

As shown in FIG. 4C, a second SiO₂ film as a second insulating film with a thickness of 1 urn is formed on the entire surface. A first through hole 50 is formed so as to expose the first SiO₂ film 12 a surface, a portion of the TiN films 16 a, and a portion of the Ti films 17 a in the second SiO₂ film. A portion of the first SiO₂ film 12 a is removed. As a result, a portion of the TiN films 16 a sidewalls is exposed. Here, an etching depth is about the half thickness of the first main interconnection 19.

As shown in FIG. 4D, a second interconnection recess 24 with a thickness of 500 nm is formed in the second SiO₂ film 22 using plasma etching with C₂F₈ gas and O₂ gas.

As shown in FIG. 4E, a second TiN film 26 and a second Ti film 27 are successively formed on the second SiO₂ film in the second interconnection recess using the same manner of the forming steps for the first interconnection 18.

As shown in FIG. 4F, Cu is buried in the second interconnection recess 24 using a sputtering method or CVD method. Then, the Cu is polished until the second SiO₂ film 22 surface is exposed.

A second interconnection 28 which is made up of Cu as a second main interconnection, the second TiN film 26, and the second Ti film 27, are formed in the second interconnection recess 24. Thus, the second interconnection 28 is connected to the first TiN film 16 a and the first Ti film 17 a.

FIGS. 5A-5F are cross-sectional views showing a method for forming a damascene interconnection structure according to a second preferred embodiment.

As shown in FIG. 5A, a first insulating film 12 is preferably made up of SiO₂ film 34, SiN film 32, and SiO₂ film 30. The SiO₂ film 34 with a thickness of 500 nm is formed on semiconductor substrate 10. The SiN film 32 as an etching stop layer with a thickness of 50 nm is formed on the SiO₂ film 34. The SiO₂ film 30 with a thickness of 500 nm is formed on the SiN film 32.

Then, the SiO₂ film 30 is etched using a photolithography technique and plasma etching with C₂F₈ gas and O₂ gas. At this time, SiN film 32 serves as the etching stop layer against the SiO₂ film 30. As a result, the SiO₂ film patterns 12 a, 30 and a first interconnection recess 14 are formed, respectively.

As shown in FIG. 5B, TiN films 16, 16 a, Ti films 17, 17 a, and first main interconnections 19 are respectively formed in the first interconnection recess 14 using the same manner for forming steps of the first preferred embodiment. Here, a first interconnection 18 is made up of the TiN films 16, 16 a, the Ti films 17, 17 a, and the first main interconnections 19.

As shown in FIG. 5C, a second insulating film 22 is preferably made up of SiO₂ film 44, SiN film 42, and SiO₂ film 40. The SiO₂ film 44 with a thickness of 500 nm is formed on the entire surface. The SiN film 42 as an etching stop layer with a thickness of 50 nm is formed on the SiO₂ film 44. The SiO₂ film 40 with a thickness of 500 nm is formed on the SiN film 42.

The SiO₂ film 40 is etched using a photolithography technique and plasma etching with C₂F₈ gas and O₂ gas until the SiN film 42 is exposed. Then, the SiN film 42 is etched using plasma etching with SF₆ gas and O₂ gas. Then, the SiO₂ films 12, 44 are etched using a photolithography technique and plasma etching with C₂F₈ gas and O₂ gas until the SiN film 32 is exposed. As a result, a through hole 50 is formed, and a sidewall of the TiN film 16 a, edge of the Ti films 17 a, and a part of the first main interconnections 19 are exposed in the through hole 50.

As shown in FIG. 5D, a second interconnection recess 24 which is wider than the through hole 50, is formed by etched the SiO₂ film 40 using a photolithography technique and plasma etching with C₂F₈ gas and O₂ gas.

As shown in FIG. 5E, a second TiN film 26 mad a second Ti film 27 are successively formed in the second interconnection recess 24 and the through hole 50 using the same manner of the forming steps for the first interconnection 18. Here, before forming the second TiN film 26 and the second Ti film 27, another Ti film may be formed in the second interconnection recess 24 and the through hole 50, The first main interconnections 19 are subjected to NH₃ for forming the second TiN film 26. As a result, the first main interconnections 19 nitrides, and it is difficult to electrically connect between the first interconnection 18 and the second interconnection 28.

As shown in FIG. 5F, Cu is buried in the second interconnection recess 24 using a sputtering method or CVD method. Then, the Cu is polished until the second SiO₂ film 22 surface is exposed.

A second interconnection 28 which is made up of Cu as a second main interconnection, the second TiN film 26, and the second Ti film 27, are formed in the second interconnection recess 24. Thus, the second interconnection 28 is connected to the first TiN film 16 a and the first Ti film 17 a.

FIG. 6 is a plan view showing a damascene interconnection structure according to a third preferred embodiment. FIG. 7 is a cross-sectional view showing a damascene interconnection structure according to the third preferred embodiment.

As shown in FIG. 6 and FIG. 7, a first interconnection 38 is preferably made up of a TiN film 16 as a barrier layer, a Ti film 17 as a conductive layer, and a first main interconnection 19 comprising a Cu. The first interconnection 38 is formed in a first SiO₂ film 12. A second interconnection 48 is preferably made up of a TiN film 26 as a barrier layer, a Ti film 27 as a conductive layer, and a first main interconnection 29 comprising a Cu.

The second interconnection 48 is formed so as to cover an upper surface of and a sidewall of the first interconnection 38.

Since a connecting area is wider than in the conventional art, a contact resistance is low and current flow is easy. Therefore, electromigration cam be avoided.

In the structure mentioned above, when a voltage so as to become a high voltage is applied to the first interconnection 38 and a voltage so as to become a low voltage is applied to the second interconnection 48, electrons flows from the second interconnection 48 to the first interconnection 38. The Cu atoms in the first main interconnection 19 of the first interconnection 38 move in opposite direction of electron flow because of electromigration. As a result, voids are formed in the first main interconnection 19 of the first interconnection 38. However, since the second interconnection 48 is connected to the first Ti 17 a, the first Ti 17 a can maintain electrical connection between the first and second interconnections.

While the present invention has been described with reference to the illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to those skilled in the art on reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention. 

1. A semiconductor device comprising: a first insulating layer having a through hole; a first interconnection comprised a first conductive layer, a first barrier layer, and a first main interconnection, the first conductive layer formed on the first insulating layer in the first through hole, the first barrier layer formed on the first conductive layer, and the first main interconnection formed on the first barrier layer so as to bury the through hole; and a second interconnection connected to one of the first conductive layer and the first barrier layer.
 2. A method of forming a semiconductor device comprising: forming a first insulating layer having a through hole; forming a first interconnection comprised a first conductive layer, a first barrier layer, and a first main interconnection, the first conductive layer formed on the first insulating layer in the first through hole, the first barrier layer formed on the first conductive layer, and the first main interconnection formed on the first barrier layer so as to bury the through hole; and forming a second interconnection connected to one of the first conductive layer and the first barrier layer. 